this page on the california board of vocational nursing and psychiatric technicians tells you the qualifications to take the nclex-pn exam by equivalency education which is what you are proposing. http://www.bvnpt.ca.gov/method3.htm
i didn't look at their online application, but i researched this for another member a week or so ago who lives in another state. the various states have specific rules as to how they verify your education. california seems to want transcripts of your grades. some states want letters from the deans of the nursing programs
verifying that the curriculum of the program meets their licensing requirements for lvn/lpn education. you could call california bvnpt to clarify if you would qualify to take the nclex-pn as a current rn student. i don't think that the intent of equivalency, however, was meant to extend to rn students who need to get employment while in school. otherwise, rn students would be testing in huge numbers for this license. also, it is my understanding that it is illegal to hold an rn and lvn license at the same time in california. you would have to surrender any lvn license you had upon passing the nclex. i'll tell you what i told the student who was also thinking of doing what you are. . .i do not believe that you would be able to handle a new job as a new lvn and continue your studies as an rn student. too much stress. you will fail at one or the other, if not both. i believe the intent of allowing people to sit for nclex-pn is when they have continuously failed to pass the nclex and do not want their education to go to waste or they have been unable to complete their rn course of training for some reason. people also need to know that becoming licensed by this method in california does not necessarily guarantee reciprocity with other states if you ever move out of state.
make sure you check out the nursing student forums. here is a list of them: https://allnurses.com/forums/f196/
hope to be seeing you there. welcome to allnurses!